With JSPM The loading times are slow even for bundled apps. From looking at the timeline profile it is mostly JS execution time.

The `else` keyword really does work well in Vue, you should really consider it. It's just that a lot of time we have if.bind='stuff' immediately followed by if.bind='!stuff', and 'stuff' can get complicated.

And for the Object.observe, I do not know how Vue does it but it doesn't have those issues, maybe you can use a similar solution ?

Anyway I'll file bugs and we can continue the discussion on the tracker.